EXCITONIC OPTICAL NONLINEARITY OF DIELECTRIC NANOCOMPOSITES IN WEAK OPTICAL FIELDS

control of the optical properties of nanoparticles by laser fields

در این پایان نامه، درهمتنیدگی بین یک سیستم نقطه کوانتومی دوگانه(مولکول نقطه کوانتومی) و میدان مورد مطالعه قرار گرفته است. از آنتروپی ون نیومن به عنوان ابزاری برای بررسی درهمتنیدگی بین اتم و میدان استفاده شده و تاثیر پارامترهای مختلف، نظیر تونل زنی(که توسط تغییر ولتاژ ایجاد می شود)، شدت میدان و نسبت دو گسیل خودبخودی بر رفتار درجه درهمتنیدگی سیستم بررسی شده اشت.با تغییر هر یک از این پارامترها، در...

Ultrafast optical nonlinearity in poly„methylmethacrylate...-TiO2 nanocomposites

With 780-nm, 250-fs laser pulses, ultrafast optical nonlinearity has been observed in a series of thin films containing poly~methyl methacrylate! (PMMA)-TiO2 nanocomposites, which are synthesized by a simple technique of in-situ sol-gel/polymerization. The best figures of merit are found in one of the films prepared with a 60 wt % of titanium isopropoxide. Transmission electron microscopy shows...

Optical nonlinearity enhancement of graded metal-dielectric composite films

– We have derived the local electric field inside graded metal-dielectric composite films with weak nonlinearity analytically, which further yields the effective linear dielectric constant and third-order nonlinear susceptibility of the graded structures. As a result, the composition-dependent gradation can produce a broad resonant plasmon band in the optical region, resulting in a large enhanc...

All-optical excitonic transistor.

We demonstrate experimental proof of principle for all-optical excitonic transistors where light controls light by using excitons as an intermediate medium. The principle of operation of all-optical excitonic transistors is based on the control of exciton fluxes by light.

Optical Communication with Weak Coherent Light Fields